Roller traction drive

ABSTRACT

A single input, contrarotating, equal speed reduction ratio, dual output roller traction drive mechanism, wherein the single input is effective from the input shaft to both the outer ring of a first friction gearing unit and split suns of a second friction gearing unit. A fixed but flexible reaction member is attached through the carrier of the second unit to split suns of the first unit. One output shaft is rotated by the carrier of the first unit, while the other output shaft is rotated by the outer ring of the second unit. Both friction gearing units include identical corresponding radii. Dual torque loader mechanisms vary internal preload in proportion to torque transmitted by causing the two outermost suns of the first and second split sun sets to move axially, with the members interconnecting the two friction gearing units and on portions of which the two sets of suns are mounted flexing in response to the axial movement of the two outermost suns to permit a corresponding axial movement of the two innermost suns.

United States Patent 5] Feb. 15, 1972 Hewko [54] ROLLER TRACTION DRIVE[72] Inventor: Lubomyr 0. Hewko, Port Clinton, Ohio [73] Assignee:General Motors Corporation, Detroit,

Mich.

[221 Filed: Nov. 25, 1969 [21] Appl. No.: 879,701

[52] US. CL ..74/665 K, 74/798 [51] ...Fl6h 37/06,Fl6h 13/06 [58] Fieldof Search ..74/665 K, 798, 796

[56] References Cited UNITED STATES PATENTS 1,368,570 2/1921 Philippeau..74/798 2,853,899 9/1958 Graham et al ...74/796 3,252,355 5/1966 Hewko..74/796 3,304,804 2/1967 Oldfield et a1. ..74/665 3,475,993 11/1969Hewko ..74/798 Primary Examiner-Arthur T. McKeon Attorney-Warren E.Finken, A. M. Heiter and John P. Moran [57] ABSTRACT A single input,contrarotating, equal speed reduction ratio, dual output roller tractiondrive mechanism, wherein the single input is effective from the inputshaft to both the outer ring of a first friction gearing unit and splitsuns of a second friction gearing unit. A fixed but flexible reactionmember is attached through the carrier of the second unit to split sunsof the first unit. One output shaft is rotated by the carrier of thefirst unit, while the other output shaft is rotated by the outer ring ofthe second unit. Both friction gearing units include identicalcorresponding radii. Dual torque loader mechanisms vary internal preloadin proportion to torque transmitted by causing the two outermost suns ofthe first and second split sun sets to move axially, with the membersinterconnecting the two friction gearing units and on portions of whichthe two sets of suns are mounted flexing in response to the axialmovement of the two outermost suns to permit a corresponding axialmovement of the two innermost suns.

15 Claims, 3 Drawing Figures PATEFEBFEB 15 I372 INVIiNTOR.

ATTORNEY ROLLER TRACTION DRIVE This invention relates to friction drivemechanisms and more particularly to double-stage, split-power rollertraction drive mechanisms.

In underwater vehicle applications, such as submarines and torpedodrives, as well as some surface applications, it is desirable to haveone input and two contrarotating equal speed ratio propeller outputs inorder to substantially eliminate the net reaction torque which tends torotate the vehicle about its longitudinal axis. It is also desirable tohave a quiet, vibrationfree and efficient operation, wherein the twopropellers run at a predetermined reduced speed from that of the primemover.

Accordingly. an object of the invention is to provide an improved singleinput, dual contrarotating output, friction drive mechanism, wherein theoutputs are both at the same reduced speed ratio.

Another object of the invention is to provide a dual friction gearingdrive mechanism wherein the corresponding radii of the two units areidentical.

A further object of the invention is to provide a dual friction gearingdrive mechanism wherein the members interconnecting the two units areflexibly attached therebetween so as to cooperate with the torque loadermechanisms to cause the mating split sun halves of the two sets of sunsto move axially toward or away from one another, as required tocompensate for increased or decreased torque, respectively, withoutaffecting the distance between the centers of the two units.

A still further object of the invention is to provide a contrarotatingpropeller drive mechanism wherein some particular, practical speedreduction ratio is attainable for each of the contrarotating outputs.

Still another object of the invention is to provide a friction drivemechanism which is adaptable for either ballor rollertype intermediatemembers.

These and other objects and advantages of the invention will becomeapparent when reference is made to the following specification andaccompanying drawings, wherein:

FIG. 1 is a partial cross-sectional view of a roller traction drivemechanism embodying the invention;

FIG. 2 is a fragmentary cross-sectional view taken along the plane ofline 22 of FIG. 1, as if FIG. 1 were a full round view, and looking inthe direction of the arrows; and

FIG. 3 is a cross-sectional view taken along the plane of line 3-3 ofFIG. 1, as if FIG. 1 were a full round view, and looking in thedirection of the arrows.

Referring now to the drawings in greater detail, FIG. 1 illustrates aroller traction drive mechanism having a single input shaft 12 and dualcontrarotating, concentric output shafts l4 and 16 mounted in a fixedhousing 18. The input shaft 12 is driven by a suitable prime mover orengine (not shown) via internal splines 19, and extends into the housing18 through an inlet opening 20 formed in an end cover 21, wherein it issupported on bearings 22. The bearings 22 are confined against axialmovement by means of a shoulder 23 formed in the inlet opening 20 and aretainer ring 24 mounted on the end cover 21. The end cover 21 issecured to the hous' ing 18 by any suitable means, such as bolts 25.

The outermost concentric output shaft 14 extends from the other end ofthe housing 18, through an outlet opening 26, wherein it is supported onbearings 27, the latter being confined against axial movement by meansofa shoulder 28 in the outlet opening 26 and a retainer ring 29 mountedon the housing 18. The inner concentric output shaft 16 extends axiallythrough the hollow outer output shaft 14 and is supported therein onbearings 30 mounted between the inner and outer peripheries of the outerand inner concentric shafts 14 and 16, respectively. The bearings 30 areconfined against axial movement by means of shoulders 31 and 32 andretainer rings 33 and 34 on the outer and inner output shafts 14 and 16,respectively. The shoulder 32 may be the end face of a separate sleevemember 35 held in place on the inner output shaft 16 by a retainer ring36.

A flange 37, formed on the input shaft 12 just inside the end cover 21of the housing 18, is secured to one end 38 of a contoured ring 39 of afirst friction gearing drive assembly 40 by any suitable means, such asbolt 41. An angled flex member 42 includes a flangelike axial springportion 43 and a cylindrical extension portion 44 and is connectedbetween the other end 45 of the contoured ring 39 and a pair ofcontoured suns 46 and 48 of a second friction gearing drive assembly 50.As will be explained, the flange-shaped portion 43 functions similarlyto a Belleville spring and is secured adjacent the outer edge thereof tothe end 45 of the ring 39 by bolts 51. The sun 46 is secured to thecylindrical member 44 adjacent a shoulder 52, while the sun 48 isslidably and rotatably mounted on the cylindrical member 44 in a mannerto be described. A ball member 53 is radially located between thecontoured surface portions of the pair of suns 46 and 48 and a contouredring 54 of the second drive unit 50. A carrier 55 surrounds the ballmember 53 and is secured to a reaction member 56 by bolts 57. The member56 is secured to the housing 18 by splines 58 and restrained axiallythereon by a shoulder 59 and a retainer ring 60. It should be noted atthis point that the opening through the carrier 55 is large enough thatany movement of the carrier 55 in an axial direction in FIG. 1 will notcontact the ball member 53.

A second angled flex member 61 includes a flangelike axial springportion 62 connected by bolts 63 to the carrier 55 and a cylindricalextension portion 64. The member 61 extends between the carrier 55 and apair of adjacent contoured suns 65 and 66 of the first planetary unit40. The flange-shaped portion 62, like the other flanged member 43,functions similarly to a Belleville spring, as will be seen hereinafter.The sun 65 is secured to the member 64 adjacent a shoulder 67, while thesun 66 is slidably mounted on the member 64 in a manner to be described.A second ball planet 68 is radially located between the contouredsurface portions of the pair of suns 65 and 66 and the contoured ring 39of the first planetary unit 40. A second carrier 70 surrounds the ballplanet 68, and a carrier member 72 is connected by bolts 74 and key 76between the carrier 70 and the innermost output shaft 16, respectively.The carrier 70 does not contact the ball planet 68 in an axial directionin FIG. 1. The ring 54 of the second drive unit 50 drives the outermostoutput shaft 14 by means of a flange member 78 formed on the shaft 14and connected to the ring 54 by bolts 80 just inside the output end ofthe housing 18.

A pair of needle bearing assemblies 82 and 84 rotatably support the flexmember 61 on the innermost concentric output shaft 16. Another set ofneedle bearings 86 rotatably supports the input end of the innermostoutput shaft 16 within a recess 88 formed in the input shaft 12.

A first seal ring 90 is mounted between the input shaft 12 and the inletopening 20 in the end cover 21, adjacent the outer face 92 of the fixedbearings 22. A second seal ring 94 is mounted between the outer outputshaft 14 and the outlet opening 26 in the housing 18 at the output endthereof adjacent the outer face 96 of the fixed bearings 27. A thirdseal ring 98 is mounted between the two output shafts 14 and 16 adjacentthe outer face 99 of the bearings 30. Additional 0- ring seals 100, 101and 102 are mounted in grooves formed in the housing 18, the outputshaft 14 and the output shaft 16, respectively.

Splines 103 and 104 are formed on the output ends of the shafts 14 and16 for connection with suitable members to be driven, such as a pair ofpropellers (not shown).

The input shaft 12 is held against axial movement by a shoulder 106 anda retainer ring 108 abutting against the end faces of the fixed bearings22. The outermost output shaft 14 is held against axial movement by ashoulder 110 and a sleeve member 112 adjacent the end faces of the fixedbearings 27. The sleeve member 112 is held against the face 96 of thefixed bearings 27 by a nut 114 threadedly mounted on the outer outputshaft 14 inwardly of the splines 103.

The inner output shaft 16 is held against axial movement by the retainerring 34 and the sleeve member 35 adjacent the end faces of the bearings30, previously described as being fixed on the inside surface of thehollow output shaft 14 by the shoulder 31 and the retainer ring 33. Anut 116 is threadedly mounted adjacent the inner end of the innermostoutput shaft 16 and abutted against the carrier member 72 to hold thelatter against a shoulder 118 formed on the inner shaft 16, therebypositioning the carrier 70 relative to the ball planet 68.

A first torque loader mechanism 120 is mounted on the forward end of theflex member 61 between the sun 66 of the first planetary unit 40 and aretainer ring 122 mounted on the end of the cylindrical portion 64 ofthe flex member 61. A second torque loader mechanism 124 is mounted onthe rearward end of the flex member 42 between the sun 48 of the seconddrive unit 50 and a retainer ring 126 mounted on the end of thecylindrical portion 44 of the flex member 42. The torque loaders 120 and124 include similar ball ramp members 128 and 130 and balls 132 and 133,respectively. The balls 132 and 133 are confined between irregular rampsurfaces 134 and 135 (FIG. 3) formed on the ball ramp members 128 and130 and the adjacent suns 66 and 48, respectively, and the ramp members128 and 130 are secured by respective splines 136 and 138 to the flexmembers 61 and 42. The mechanisms 120 and 124 are similar to the spacedtorque-sensing ball ramp devices described in U.S. Pat. No. 3,283,614,issued on Nov. 8, 1966 in the name of the Applicant, except that thedevices in the patent function on opposing sides of adjacent axiallymovable split suns, rather than on the outermost halves of two sets ofsplit suns, each set of which includes one fixed sun and one axiallyslidable sun.

Referring now to FIG. 2, it may be noted that there are eight ballmembers 53 and 68 in each of the drive units 40 and 50. Torque forcesare transmitted between the balls 53 and 68 and their respectivecarriers 55 and 70 through partial spherical, hydrodynamic journalbearing surfaces created between the ball members and oppositelydisposed cuplike slidable inserts 140 and 142, by virtue of thespherical surfaces 144 of the in serts 140 and 142 having a slightlylarger radius than that of the balls 53 and 68, providing a wedgedopening therebetween, whereby lubricant in the wedged opening can liftthe ball members 53 and 68 for full hydrodynamic spheri cal bearinglubrication. The inserts 140 and 142 are thus effectively confinedbetween opposite sides of the balls 53 and 68 and their respectivesurrounding carriers 55 and 70. In other words, while there is nocontact between the ball members 53 and 68 and their adjacent carriers55 and 70, respectively, in the axial direction (FIG. 1), there is adirect connection between the ball members 53 and 68 and the carriers 55and 70 in the plane of FIGv 2 through the intermediate inserts 140 and142.

OPERATION Assume now that the input shaft 12 is being rotated clockwiseas viewed from the left in FIG. 1 by any suitable prime mover (notshown). The ring 39 of the first planetary unit 40 will likewise berotated clockwise by interconnecting flange 37. Nonslipping frictionalengagement between the ring 39 and the planet balls 68 will rotate thelatter in a clockwise direction about the suns 65 and 66. The sun 65 andthe ramp member 128 are held against the rotation by virtue of bothbeing directly connected to the fixed cylindrical member 64, the sun 66being slidably and rotatably mounted on the member 64. The balls 132 andthe ramp member 128 urge the sun member 66 to rotate and move axially onthe member 64, as required to accommodate relative ramp displacement dueto torque forces. The member 64, of course, is held against rotation bythe carrier 55 and the reaction member 56, the latter being secured tothe housing 18 by the splines 58.

The carrier 70 of the first planetary unit 40 is thus caused to rotatein a clockwise direction. Since the carrier 70 is secured to theinnermost output shaft 16 by the key 76, the shaft 16 will, likewise, berotated in a clockwise direction.

As previously described, the ring 39 of the first planetary unit 40 isconnected by the flex member 42 to the suns 46 and 48 of the seconddrive unit 50, causing the suns 46 and 48 to rotate in a clockwisedirection with the ring 39. This will cause the ball members 53 torotate in place within the bearing inserts 140 and 142 in acounterclockwise direction, inasmuch as they are restrained fromrotation about the axis of the housing 18 by the fixed carrier 55 andthe fixed reaction member 56. The counterclockwise spinning rotation ofthe ball members 53 will cause the ring 54 to rotate in acounterclockwise direction, and the ring, in turn, via the flange 78,will rotate the outermost output shaft 14 in a counterclockwisedirection, or in a direction opposite to that of the other concentricout' put shaft 16.

At this point it should be noted that throughout the abovedescribedoperation, the axial centers of the drive assemblies 40 and 50 remain ina fixed distance apart at all times. However, as torque increases, forexample, the sun halves 46/48 and 65/66 all approach their respectivemating halves. This axial movement of the individual split suns isaccomplished by virtue of the balls 132 and 133 moving under theincreased torque in a direction which both moves the outermost sunhalves 48 and 66 toward their mating sun halves 65 and 46, respectively,and urges the ramp members 128 and 130 outwardly away from theirrespective adjacent sun halves 66 and 48. This outward pressure on theramp members 128 and 130 is transferred through the retainer rings 122and 126 to the cylindrical members 64 and 44 and thence to the flexibleflange members 62 and 43, respectively. Movement of the flexible flangemembers 62 and 43 is in a direction which, by virtue of the shoulders 67and 52, causes the other sun halves 65 and 46 to move their respectivemating sun halves 66 and 48 the same distance as the above-describedaxial movement of the latter.

It should be further noted at this point that the spring rate of theBelleville-springlike flange members 43 and 62 must be compatible withthe torque loader and 124 characteristics. To effect a desiredrelationship, the thicknesses of the flange members 43 and 62 may becorrespondingly varied throughout the radial spans thereof, such as bytapering, dishing, and or contouring their respective cross sections.

With the two drive units 40 and 50 interconnected in the above-describedmanner such that for one input there are two opposite rotationaloutputs, it will now be shown that the speed ratios of both outputs areidentical.

As illustrated in FIG. 2, let:

R sun radius R, =ring radius R, planet-sun radius R,,,.= planet-ringradius N, sun r.p.m. N, carrier r.p.m.

N, ring r.p.m. N, planet r.p.m.

R speed reduction ratio of the respective rotating drive unit elements,i.e., NJN for unit 40 and l\,/l l for unit 50.

Additionally, let the radii of corresponding components of the two driveunits be equal.

Then for any traction drive, one can write the following kinematicrelationship:

NA r pa l pr) r r pa+ s a pr I) Now, let subscript 1 denote the firstplanetary unit 40, and subscript 2 denote the second drive unit 50. N,,=0, by virtue of the suns 65 and 66 being fixed through the members61, 55 and S6 to the housing 18. Hence, we can see from equation I)that:

(Subscripts l and 2 can be omitted from the radii, since correspondingradii of the two drive units are equal.)

The speed reduction ratio of the first unit, therefore, becomes:

RsRpr or, for N, ()1

|'l Rs-R n' R l 1 i'] r px V 7 WI- W W "7b 22 Similarly, since N =0,equation (1) becomes:

=N R,R,,,+N, R,R and the speed reduction ratio of the second unitbecomes:

sz! r ps r2 s pr For contrarotation the speed reduction ratios of bothunits must be the same in absolute value but opposite in sign.Therefore:

The value of the ratio can be computed by equating equation (2) toequation (3). But first, substituting in the two exprcssions:

li,/R,. R,,,./R,,,=K Then, the equations (2) and (3) can be rewrittenas:

I ,=-N,,/N,.,=I+K

(6) and R =N,, /N, =l/K 7 Further, since there are one input and twooutputs, and in view of the above-described interconnections:

rl s2 in N N (first output) (8) N N (second output) Now, solvingequation (4) by using equations (6) and (7):

It is obvious from equation (5) that K must always be positive, negativeradii being meaningless in equation (I). Therefore, (9) can berewritten, for K 2 0, as:

leads to K 0, thus violating restriction K E 0, and is disregarded.

Proceed now to calculate the speed reduction ratio which satisfies thecontrarotating outputs with two similar drive units. Substitutingequation (1 l) in equation (6):

Similarly, substituting equation l l in equation (7):

l 2 2 .618 l+\/ 1+\/ 1.23s 1 It is apparent that there is one commonratio, namely, 1.618, which can be obtained from a particular geometricrelationship of friction gearing drive components. As determined above,this geometric relationship may be defined as:

For a simple drive mechanism, R,,,=R,,,; therefore, R,,, R,,,=l, and thesimplified geometric drive relationship is:

While the above description and calculations relate to identicalcorresponding friction gearing radii in dual units, in an applicationwherein it is required that the outputs from the dual units bedifferent, such as where some accessory device is to be actuated by oneof the two output shafts, or for any other reason, it is merelynecessary to change the sun radius to ring radius ratios of the twounits as required.

Now, in those applications wherein R does not equal R such as could bethe case if the points of contact between the ball planet and itsassociated ring and split suns were substantially different asrepresented by points A," B" and C of planetary unit 40 (FIG. 1), ratherthan points A" and D," causing the radial distance from the center ofthe ball planet 68 to a line connecting points 8" and C" to be shorterthan the radial distance from the center of the ball planet 68 to thepoint D" the following relationship would be applicable:

As illustrated in FIG. 1, let R, equal the distance between the centerof the planet and the point of contact with either split sun, and let orequal the angle subtended by the intersection of the tangent throughpoint B and the axis of the drive unit. Then:

ps nr pt( lco5a When the intermediate member is a ball, R,,,=R,,,.Therefore: R,,,=R ,,,-R,,,( lcosa Now, should the pianet be a barrelroller, such as described in the above-mentioned US. Pat. No. 3,283,614,which is not a portion of a sphere, applying equation (14) to equation(12):

lt should be noted that the above-described controlled common speedratio will also be attainable for a traction drive mechanism 10 whereinthe reaction member 56 is secured to the housing 18 by being axiallyslidably mounted on the splines 58. In this event, the flange portion 62may be rigid, with the above-described axial movement of the member 64being possible as a result of the sliding action of the member 64 alongthe splines 58 while serving as the reaction means. Furthermore, theoutput flange member 78 may bethe flexible member, while the flangeportion 43 may be a rigid member, in which case, under increased torque,the torque loader ball 133 will move the sun half48 toward thestationary sun half 46, thereby moving the ball 53 of the secondfriction gearing unit to the left in FIG. 1. Such action will move thesecond unit ring 54 to the left, keeping the sun and ring centersaligned and flexing the flange member 78.

In summary, it is evident that the invention provides a contrarotatingtraction drive mechanism that is economical and readily manufacturablein that friction gearing elements having substantially identical radiiare employed in the dual drive units.

It is further evident that the invention provides an improved structuralarrangement wherein a controlled common speed ratio is readilyattainable for the dual contrarotating outputs.

It is still further evident that the invention is adaptable to roller,ball and gear drive arrangements.

While basic embodiments of the invention have been shown and described,other modifications thereof are possible.

lclaim:

l. A friction drive mechanism comprising a housing, a power input shaftrotatably supported in said housing, first and second contrarotatingpower output shafts, a first planetary speed reducing unit operativelyconnected between said input shaft and said first output shaft, a secondspeed reducing unit operatively connected between said first planetaryunit and said second output shaft, and at least one flexibletorqueresponsive member operatively connected among said first andsecond speed-reducing units and said power input and power outputshafts.

Z. A friction drive mechanism comprising a housing, a power input shaftrotatably supported in said housing, first and second contrarotatingpower output shafts, a first friction gearing unit operatively connectedbetween said input shaft and said first output shaft, a second frictiongearing unit operatively connected between said first friction gearingunit and said second output shaft, a pair of flexible membersinterconnecting portions of said first and second friction gearingunits, and means operatively connected to said pair of flexible membersfor causing said pair of flexible members to flex in response to thetorque applied to said first and second units.

3. The friction drive mechanism described in claim 2, wherein said firstfriction gearing unit includes first, second and third planetarymembers, and said second friction gearing unit includes fourth, fifthand sixth members, one of said pair of flexible members being connectedbetween said first and said sixth members, and the other of said pair offlexible members being connected between said third and fifth members.

4. The friction drive mechanism described in claim 3, wherein said meansfor causing said flexible members to flex is operatively connected tosaid third and sixth members.

5. The friction drive mechanism described in claim 4, wherein said thirdand sixth members are first and second sets of split suns, respectively,one-half of each set of which is slidably mounted on the respectiveflexible members adjacent said means for causing said pair of flexiblemembers to flex, and the other half of each set of which is secured tosaid respective flexible members adjacent said one-half of each set.

6. A friction drive mechanism comprising a housing, a power input shaftrotatably supported in said housing, first and second contrarotatingpower output shafts, a first planetary speed reducing unit includinginput, output and fixed members and operatively connected between saidinput shaft and said first output shaft, a second speed reducing unitincluding input, output and fixed members and operatively connectedbetween said first planetary unit and said second output shaft, a firstflexible torque-responsive member interconnecting the input members ofsaid first and second speed reducing units, and a second flexibletorque-responsive member interconnecting the fixed members of said firstand second units.

7. A friction drive mechanism comprising a housing, a power input shaftrotatably supported in said housing, first and second contrarotatingpower output shafts, a first planetary speed reducing unit including afirst input member, a first output member and a first fixed member, asecond speed reducing unit including a second input member, a secondoutput member and a second fixed member, means for connecting said firstinput member to said input shaft for rotation therewith, means fordriving said second input member from said first input member, reactionmeans connected between said housing and said second fixed member, meansfor connecting said first fixed member to said second fixed member,means for connecting said first power output shaft to said first outputmember for rotation therewith, and means for connecting said secondpower output shaft to said second output member for rotation therewith,

8. A friction drive mechanism comprising a housing, a power input shaftrotatably supported in said housing, first and second contrarotatingpower output shafts, a first planetary speed reducing unit including afirst ring, a first sun, a first planet frictionally engaging said firstring and said first sun, :1 first carrier operatively connected to saidfirst planet, a second speed reducing unit including a second ring, asecond sun, a

second member frictionally engaging said second ring and said secondsun, a second carrier operatively connected to said second member, firstmeans for connecting said first ring to said input shaft for rotationtherewith, second means for connecting said second sun to said firstring for rotation therewith, reaction means connected between saidhousing and said second carrier, third means for connecting said firstsun to said second carrier, fourth means for connecting said first poweroutput shaft to said first carrier for rotation therewith, and means forconnecting said second power output shaft to said second ring forrotation therewith.

9. The friction drive mechanism described in claim 8, wherein said firstsun includes first and second split sun halves, and said second sunincludes third and fourth split sun halves, and a first torque-loadingunit mounted on said third means for connecting said first sun to saidsecond carrier adjacent said first sun half for slidably moving saidfirst sun half in response to applied torque, a second torque-loadingunit mounted on said second means for connecting said second sun to saidfirst ring adjacent said fourth sun half for slidably moving said fourthsun half in response to applied torque.

10. The friction drive mechanism described in claim 9, wherein each ofsaid means for connecting said first sun to said second carrier and saidmeans for connecting said second sun to said first ring includesflexible means for causing said second and third sun halves,respectively, to move axially a distance corresponding to that of theslidably moving first and fourth sun halves, respectively, and in thedirection opposite thereto.

11. The friction drive mechanism described in claim 8, wherein saidsecond means includes a first cylindrical member having a first collarformed on one end thereof, said second sun being mounted on the otherend thereof, and said first collar being secured adjacent the outer edgethereof to said first ring; and said third means includes a secondcylindrical member having a second collar formed on one end thereof,said first sun being mounted on the other end thereof, and said secondcollar being secured adjacent the outer edge thereofto said secondcarrier; and bearing means mounted between the outer surface of saidfirst power output shaft and the inner surface of said secondcylindrical member.

12. A friction drive mechanism comprising a housing, a power input shaftrotatably supported in said housing, first and second contrarotatingpower output shafts, a first friction gearing unit including a firstring, a first sun, a first intermediate member frictionally engagingsaid first ring and said first sun, a first carrier operativelyconnected to said first intermediate member, a second friction gearingunit including a second ring, a second sun, a second intermediate memberfrictionally engaging said second ring and said second sun, a secondcarrier operatively connected to said second intermediate member, afirst flange means connecting said first ring to said power input shaftfor rotation therewith, first flexible connector means interconnectingsaid first ring and second sun for adjusting said second sun in responseto torque changes, reaction means mounted on said housing and supportingsaid second carrier, second flexible connector means interconnectingsaid second carrier and said first sun for adjusting said first sun inresponse to said torque changes, rigid connector means for connectingsaid first power output shaft to said first carrier for rotationtherewith, and second flange means connecting said second power outputshaft to said second ring for rotation therewith.

13. A friction drive mechanism comprising a housing, a power input shaftrotatably supported in said housing, first and second contrarotatingpower output shafts, a first planetary speed reducing unit including afirst ring, a first set of split suns, a first planet frictionallyengaging said first ring and said first set of split suns, a firstcarrier operatively connected to said first planet, a second speedreducing unit including a second ring, a second set of split suns, asecond member frictionally engaging said second ring and said second setof split suns, a second carrier operatively connected to said secondmember, first flange means for connecting said first ring to said inputshaft for rotation therewith, first flexible means for connecting saidsecond set of split suns to said first ring for rotation therewith, oneof said second set of split suns being slidably mounted on said firstflexible means and the other of said second set of split suns beingfixed thereon, fixed reaction means secured to said housing andsupporting said second carrier, second flexible means for connectingsaid first set of split suns to said second carrier, one of said firstset of split suns being slidably mounted on said second flexible meansand the other of said first set of split suns being fixed thereon,second flange means for connecting said first power output shaft to saidfirst carrier for rotation therewith, third flange means for connectingsaid second power output shift to said second ring for rotationtherewith, a first torque-loading device mounted on said first flexiblemeans for slidably moving said one of said second set of split suns inresponse to torque transmitted thereto and thereby causing said firstflexible means to flex an amount sufficient to move the other of saidsecond set of split suns through a distance corresponding to themovement of said one of said second set of split suns, and a secondtorqueloading device mounted on said second flexible means for slidablymoving said one of said first set of split suns in response to torquetransmitted thereto and thereby causing said second flexible means toflex an amount sufficient to move the other of said first set of splitsuns through a distance corresponding to the movement of said one ofsaid first set of split suns, with the distance between the centers ofsaid first and second speed reducing units remaining fixed.

14. A friction drive mechanism comprising a housing, a power input shaftrotatably supported in said housing, first and second contrarotatingpower output shafts, a first planetary speed-reducing unit including afirst ring, a first sun, a first planet frictionally engaging said firstring and said first sun, a first carrier operatively connected to saidfirst planet, a second speed-reducing unit including a second ring, asecond sun, a

second member frictionally engaging said second ring and said secondsun, a second carrier operatively connected to said second member, afirst flange means connecting said first ring to said power input shaftfor rotation therewith, flexible connector means interconnecting saidfirst ring and said second sun for adjusting said second sun in responseto torque changes, slidable reaction means mounted on said housing andsupporting said second carrier, rigid connector means interconnectingsaid second carrier and said first sun for adjusting said first sun inresponse to said torque changes, rigid connector means for connectingsaid first power output shaft to said first carrier for rotationtherewith, and second flange means connecting said second power outputshaft to said second ring for rotation therewith.

15. A friction drive mechanism comprising a housing, a power input shaftrotatably supported in said housing, first and second contrarotatingpower output shafts, a first planetary speed reducing unit including afirst ring, a first sun, at first planet frictionally engaging saidfirst ring and said first sun, a first carrier operatively connected tosaid first planet, a second speed reducing unit including a second ring,a second sun, a second member frictionally engaging said second ring andsaid second sun, a second carrier operatively connected to said secondmember, rigid flange means connecting said first ring to said powerinput shaft for rotation therewith, rigid connector meansinterconnecting said first ring and said second sun for adjusting saidsecond sun in response to torque changes, reaction means mounted on saidhousing and supporting said second carrier, flexible connector meansinterconnnecting said second carrier and said first sun for adjustingsaid first sun in response to said torque changes, rigid connector meansfor connecting said first power output shaft to said first carrier forrotation therewith, and flexible flange means connecting said secondpower output shaft to said second ring for rotation therewith.

1. A friction drive mechanism comprising a housing, a power input shaftrotatably supported in said housing, first and second contrarotatingpower output shafts, a first planetary speed reducing unit operativelyconnected between said input shaft and said first output shaft, a secondspeed reducing unit operatively connected between said first planetaryunit and said second output shaft, and at least one flexibletorque-responsive member operatively connected among said first andsecond speed-reducing units and said power input and power outputshafts.
 2. A friction drive mechanism comprising a housing, a powerinput shaft rotatably supported in said housing, first and secondcontrarotating power output shafts, a first friction gearing unitoperatively connected between said input shaft and said first outputshaft, a second friction gearing unit operatively connected between saidfirst friction gearing unit and said second output shaft, a pair offlexible members interconnecting portions of said first and secondfriction gearing units, and means operatively connected to said pair offlexible members for causing said pair of flexible members to flex inresponse to the torque applied to said first and second units.
 3. Thefriction drive mechanism described in claim 2, wherein said firstfriction gearing unit includes first, second and third planetarymembers, and said second friction gearing unit includes fourth, fifthand sixth members, one of said pair of flexible members being connectedbetween said first and said sixth members, and the other of said pair offlexible members being connected between said third and fifth members.4. The friction drive mechanism described in claim 3, wherein said meansfor causing said flexible members to flex is operatively connected tosaid third and sixth members.
 5. The friction drive mechanism describedin claim 4, wherein said third and sixth members are first and secondsets of split suns, respectively, one-half of each set of which isslidably mounted on the respective flexible members adjacent said meansfor causing said pair of flexible members to flex, and the other half ofeach set of which is secured to said respective flexible membersadjacent said one-half of each set.
 6. A friction drive mechanismcomprising a housing, a power input shaft rotatably supported in saidhousing, first and second contrarotating power output shafts, a firstplanetary speed reducing unit including input, output and fixed membersand operatively connected between said input shaft and said first outputshaft, a second speed reducing unit including input, output and fixedmembers and operatively connected between said first planetary unit andsaid second output shaft, a first flexible torque-responsive memberinterconnecting the input members of said first and second speedreducing units, and a second flexible torque-responsive memberinterconnecting the fixed members of said first and second units.
 7. Afriction drive mechanism comprising a housing, a power input shaftrotatably supported in said housing, first and second contrarotatingpower output shafts, a first planetary speed reducing unit including afirst input member, a first output member and a first fixed member, asecond speed reducing unit including a second input member, a secondoutput member and a second fixed member, means for connecting said firstinput member to said input shaft for rotation therewith, means fordriving said second input member from said first input member, reactionmeans connected between said housing and said second fixed member, meansfor connecting said first fixed member to said second fixed member,means for connecting said first power output shaft to said first outputmember for rotation therewith, and means for connecting said secondpower output shaft to said second output member for rotation therewith.8. A friction drive mechanism comprising a housing, a power input shaftrotatably supported in said housing, first and second contrarotatingpower output shafts, a first planetary speed reducing unit including afirst ring, a first sun, a first planet frictionally engaging said firstring and said first sun, a first carrier operatively connected to saidfirst planet, a second speed reducing unit including a second ring, asecond sun, a second member frictionally engaging said second ring andsaid second sun, a second carrier operatively connected to said secondmember, first means for connecting said first ring to said input shaftfor rotation therewith, second means for connecting said second sun tosaid first ring for rotation therewith, reaction means connected betweensaid housing and said second carrier, third means for connecting saidfirst sun to said second carrier, fourth means for connecting said firstpower output shaft to said first carrier for rotation therewith, andmeans for connecting said second power output shaft to said second ringfor rotation therewith.
 9. The friction drive mechanism described inclaim 8, wherein said first sun includes first and second split sunhalves, and said second sun includes third and fourth split sun halves,and a first torque-loading unit mounted on said third means forconnecting said first sun to said second carrier adjacent said first sunhalf for slidably moving said first sun half in response to appliedtorque, a second torque-loading unit mounted on said second means forconnecting said second sun to said first ring adjacent said fourth sunhalf for slidably moving said fourth sun half in response to appliedtorque.
 10. The friction drive mechanism described in claim 9, whereineach of said means for connecting said first sun to said second carrierand said means for connecting said second sun to said first ringincludes flexible means for causing said second and third sun halves,respectively, to move axially a distance corresponding to that of theslidably moving first and fourth sun halves, respectively, and in thedirection opposite thereto.
 11. The friction drive mechanism describedin claim 8, wherein said second means includes a first cylindricalmember having a first collar formed on one end thereof, said second sunbeing mounted on the other end thereof, and said first collar beingsecured adjacent the outer edge thereof to said first ring; and saidthird means includes a second cylindrical member having a second collarformed on one end thereof, said first sun being mounted on the other endthereof, and said second collar being secured adjacent the outer edgethereof to said second carrier; and bearing means mounted between theouter surface of said first power output shaft and the inner surface ofsaid second cylindrical member.
 12. A friction drive mechanismcomprising a housing, a power input shaft rotatably supported in saidhousing, first and second contrarotating power output shafts, a firstfriction gearing unit including a first ring, a first sun, a firstintermediate member frictionally engaging said first ring and said firstsun, a first carrier operatively connected to said first intermediatemember, a second friction gearing unit including a second ring, a secondsun, a second intermediate member frictionally engaging said second ringand said second sun, a second carrier operatively connected to saidsecond intermediate member, a first flange means connecting said firstring to said power input shaft for rotation therewith, first flexibleconnector means interconnecting said first ring and second sun foradjusting said secOnd sun in response to torque changes, reaction meansmounted on said housing and supporting said second carrier, secondflexible connector means interconnecting said second carrier and saidfirst sun for adjusting said first sun in response to said torquechanges, rigid connector means for connecting said first power outputshaft to said first carrier for rotation therewith, and second flangemeans connecting said second power output shaft to said second ring forrotation therewith.
 13. A friction drive mechanism comprising a housing,a power input shaft rotatably supported in said housing, first andsecond contrarotating power output shafts, a first planetary speedreducing unit including a first ring, a first set of split suns, a firstplanet frictionally engaging said first ring and said first set of splitsuns, a first carrier operatively connected to said first planet, asecond speed reducing unit including a second ring, a second set ofsplit suns, a second member frictionally engaging said second ring andsaid second set of split suns, a second carrier operatively connected tosaid second member, first flange means for connecting said first ring tosaid input shaft for rotation therewith, first flexible means forconnecting said second set of split suns to said first ring for rotationtherewith, one of said second set of split suns being slidably mountedon said first flexible means and the other of said second set of splitsuns being fixed thereon, fixed reaction means secured to said housingand supporting said second carrier, second flexible means for connectingsaid first set of split suns to said second carrier, one of said firstset of split suns being slidably mounted on said second flexible meansand the other of said first set of split suns being fixed thereon,second flange means for connecting said first power output shaft to saidfirst carrier for rotation therewith, third flange means for connectingsaid second power output shift to said second ring for rotationtherewith, a first torque-loading device mounted on said first flexiblemeans for slidably moving said one of said second set of split suns inresponse to torque transmitted thereto and thereby causing said firstflexible means to flex an amount sufficient to move the other of saidsecond set of split suns through a distance corresponding to themovement of said one of said second set of split suns, and a secondtorque-loading device mounted on said second flexible means for slidablymoving said one of said first set of split suns in response to torquetransmitted thereto and thereby causing said second flexible means toflex an amount sufficient to move the other of said first set of splitsuns through a distance corresponding to the movement of said one ofsaid first set of split suns, with the distance between the centers ofsaid first and second speed reducing units remaining fixed.
 14. Afriction drive mechanism comprising a housing, a power input shaftrotatably supported in said housing, first and second contrarotatingpower output shafts, a first planetary speed-reducing unit including afirst ring, a first sun, a first planet frictionally engaging said firstring and said first sun, a first carrier operatively connected to saidfirst planet, a second speed-reducing unit including a second ring, asecond sun, a second member frictionally engaging said second ring andsaid second sun, a second carrier operatively connected to said secondmember, a first flange means connecting said first ring to said powerinput shaft for rotation therewith, flexible connector meansinterconnecting said first ring and said second sun for adjusting saidsecond sun in response to torque changes, slidable reaction meansmounted on said housing and supporting said second carrier, rigidconnector means interconnecting said second carrier and said first sunfor adjusting said first sun in response to said torque changes, rigidconnector means for connecting said first power output shaft to saidfirst carriEr for rotation therewith, and second flange means connectingsaid second power output shaft to said second ring for rotationtherewith.
 15. A friction drive mechanism comprising a housing, a powerinput shaft rotatably supported in said housing, first and secondcontrarotating power output shafts, a first planetary speed reducingunit including a first ring, a first sun, a first planet frictionallyengaging said first ring and said first sun, a first carrier operativelyconnected to said first planet, a second speed reducing unit including asecond ring, a second sun, a second member frictionally engaging saidsecond ring and said second sun, a second carrier operatively connectedto said second member, rigid flange means connecting said first ring tosaid power input shaft for rotation therewith, rigid connector meansinterconnecting said first ring and said second sun for adjusting saidsecond sun in response to torque changes, reaction means mounted on saidhousing and supporting said second carrier, flexible connector meansinterconnnecting said second carrier and said first sun for adjustingsaid first sun in response to said torque changes, rigid connector meansfor connecting said first power output shaft to said first carrier forrotation therewith, and flexible flange means connecting said secondpower output shaft to said second ring for rotation therewith.